The invention generally relates to systems and methods for electrical signal conditioning. In particular, the systems and methods for electrical conditioning are applied to solid-state thin-film battery charging.
Electronics have been incorporated into many portable devices such as computers, mobile phones, tracking systems, scanners, etc. One drawback to portable devices is the need to include the power supply with the device. Portable devices typically use batteries as power supplies. Batteries must have sufficient capacity to power the device for at least the length of time the device is in use. Sufficient battery capacity can result in a power supply that is quite heavy and/or large compared to the rest of the device. Accordingly, smaller and lighter batteries (i.e., power supplies) with sufficient energy storage are desired. Other energy storage devices, such as supercapacitors, and energy conversion devices, such as photovoltaics and fuel cells, are alternatives to batteries for use as power supplies in portable electronics and non-portable electrical applications.
Another drawback of conventional batteries is the fact that some are fabricated from potentially toxic materials that may leak and be subject to governmental regulation. Accordingly, it is desired to provide an electrical power source that is safe, solid-state and rechargeable over many charge/discharge life cycles.
One type of an energy-storage device is a solid-state, thin-film battery. Examples of thin-film batteries are described in U.S. Pat. Nos. 5,314,765; 5,338,625; 5,445,906; 5,512,147; 5,561,004; 5,567,210; 5,569,520; 5,597,660; 5,612,152; 5,654,084; and 5,705,293, each of which is herein incorporated by reference. U.S. Pat. No. 5,338,625 describes a thin-film battery, especially a thin-film microbattery, and a method for making same having application as a backup or first integrated power source for electronic devices. U.S. Pat. No. 5,445,906 describes a method and system for manufacturing a thin-film battery structure formed with the method that utilizes a plurality of deposition stations at which thin battery component films are built up in sequence upon a web-like substrate as the substrate is automatically moved through the stations.
U.S. Pat. No. 6,805,998 (which is incorporated herein by reference) issued Oct. 19, 2004, by Mark L. Jenson and Jody J. Klaassen, and is assigned to the assignee of the present invention described a high-speed low-temperature method for depositing thin-film lithium batteries onto a polymer web moving through a series of deposition stations.
U.S. Pat. No. 7,211,351 entitled “LITHIUM/AIR BATTERIES WITH LIPON AS SEPARATOR AND PROTECTIVE BARRIER AND METHOD” by Jody J. Klassen et al. (and which is incorporated herein by reference) describes a method for making lithium batteries including depositing LiPON on a conductive substrate (e.g., a metal such as copper or aluminum) by depositing a chromium adhesion layer on an electrically insulating layer of silicon oxide by vacuum sputter deposition of 500 Å of chromium followed by 5000 Å of copper. In some embodiments, a thin film of LiPON (Lithium Phosphorous OxyNitride) is then formed by low-pressure (<10 mtorr) sputter deposition of lithium orthophosphate (Li3PO4) in nitrogen. In some embodiments of the Li-air battery cells, LiPON was deposited over the copper anode contact to a thickness of 2.5 microns, and a layer of lithium metal was formed onto the copper anode contact by electroplating though the LiPON layer in a propylene carbonate/LiPF6 electrolyte solution. In some embodiments, the air cathode was a carbon-powder/polyfluoroacrylate-binder coating (Novec-1700) saturated with a propylene carbonate/LiPF6 organic electrolyte solution. In other embodiments, a cathode-contact layer having carbon granules is deposited, such that atmospheric oxygen could operate as the cathode reactant. This configuration requires providing air access to substantially the entire cathode surface, limiting the ability to densely stack layers for higher electrical capacity (i.e., amphours). There is a need for rechargeable lithium-based batteries having improved passivation against air and water vapor with improved manufacturability, density, and reliability, and lowered cost.
The techniques herein below extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the above-mentioned needs.